Drill steel guide



June 6, 1944. h c. F. Oscoop I' 2,350,651

DRILL sTEEIJ GUIDE A Filed Dec; so, 1942 2 sheetsfsheet 1 2 22 2/2@ 2a l Y ff/f'aa f3 y un',

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June 6, 1944. c'. F. osGooD 24,350,661

I l DRILL STEEL GUIDE I Filed Dec. so. 194:2` 2 sheets-sheet 2 ZZ/622km @4 AW. wmf

Patented June 6, 1944 UNITED s'mras PATENT 21a-50,6611

Massachusetts Applicationecemher 30, 194i', Serialo. 4705365 22 claims;-

r11h-is invention relates to rock drills and more particularly to an improved guide for the drill steel of a rockdrillof the mounted type.

In rockdrills of the mounted type, the hammer motor which percussively actuates the drill steel is usually mounted onan elongatedi guiding sup. port suitably positioned in adjacency' to the workingface, and motor operated feeding means is usually provided for moving the hammer motor back-and forth along the guiding support.` There is usually provided at the forward endofI the guiding support a guideY device'for centering and guiding the drill steel during starting or spotting ofahole in the face, and such guide devicesV arev frequently automaticallyreleasedf from the drill steel` as the hammer motor approaches the guidedevice during forward feed so that accidental contact ofthe hammer motor with the guide deviceiszprohibited; and permitting move'- mentV of; the forward endfof the hammer motor forwardly past the guide device. Also under certainl circumstances, as for instance,4 subsequently to the starting of a hole Witha'short dri11- ste-el.; it is also desirable to effect automatic release. of the guide device from-the drillsteel-as thegguicler device while` the latter is-held closed;

and possible damage toY the-A drill.-

Ity is accordingly an object-ofthe present inhventien to provide an: improved drlllsteel guidewhichI is automaticallyv released from ther drill steel when the hammer motor lassumeslaf predetermined-position along-.fthe guidewaysof-itsiguidv ing lsupport irrespectiveofv the directicncfhmove.l ment or the hammer-motor along-the supportguideways-. Another object-'s toi provide an'improvedY drillsteel guide' which is lautomaticakllyl released'from the'drillsteel-as the hammer-motor isfedV either of opposite directions along; its A- further object iste-provide guiding i support; an-improved-dril1 steel` guide whichdsiautomati'- cally released. from the drill steel eitherfbyl direct engagement ofY the-hammer motor therewithf-asthe-hammer motor is fed forwardlyf along;A its`Al (Cl. 2`55-1'51r` guidingsupport or by directengagementlof the drill bit therewith-as the hammer motards fed rearwardly along .the guiding support. Yet another object is toprovide an improved drill steel 5- guide having improvedmounting means Ofor the guiding elementsY thereof and improved means for lockingtheg-ui'ding elements in steel guiding position: Astill-A further object is to provide an improveds drill steel guide having the guiding elements thereof mounted4 for bodily movement inl either? of' opposite directions from'a centrally located guiding position, and having improved meansf for locking the guiding elementsl in the centrally locatedfguiding position. AA further obof the pivoted' arm type having an` improved mounting for ther guide arms and improved meansfor lockingl the guide arms-in steelfguiding position.'Y Other objects and advantagesof the'mvention will;` however, hereinafter more full-yi appear in the: course ofy the ensuingl de'- scription and? as more particularly po'imued:` outv in4 the! appended' claims@ frfpurrps'esjor illustration pgforms'fwmcn the invention `may assume' practice;

thesev drawings! whichenniustrativeembbdihe;invention-SYassbciated Y A acrss'-4 sectional Viewv taken substangiiiiemed envenena n y Fig;- 3 isr-acros'sfsect-ionafl viewf takentsubstaririgl 4i isacross se ionai' yievv takensubstan:

nelly on linera'l rtg. 1; snowing" theguide 40,. initsrwiue-upen, norifguidirie" position;

Fig: eis naw/few iniengitudiiiaiverticn section inf steelfguiding-fpositionr Fig(- 1.1 istaffcross -sectionalview taken-"substane jectf is toil providean` improved drill steel guidey sociated with a conventional hammer rock drill of the mounted drifter type. It will be evident however, that the improved drill steel guide may l 4 be associated with rock drills of other types, such as a wagon or tower drill.

IIhe rock drill disclosed herein comprisesvaw conventional hammer motor I mourfited for movement back and forth along the guideways 2, 24 of The hammer motor y is of |a well known pressure'uid operated type a conventional guide shell 3.

position substantially midway longitudinally between the end-plates I3 and I4. The coil spring 23 at the forward sides of the guide arms is of the combined compression and torsion type and has coil portions 24 coaxial with the arm pivots and a transverse connecting portion 25 (see Fig. 4) eX- tending between and connecting the coil portions. The ends of the spring engage at 26 vthe guide arms. Thus, it is evident that the front spring 23 reacts directly between the arms and constantly tends to swing the arms toward their wide-open, noni-guiding position. When the guide arms are vcentrally located longitudinally between the endplates, they are held in guiding relation with the ,drillhsteeli byy lugs 21 yprojecting from the ann bearing hubs 2Iwand engaging the opposite vertical side surfaces 23 of a centrally located locking and stop vmember 29 lherein preferably formed having a motor cylinder 4 provided with lateral 3 guides 5, 5 received in the shell guideways. The

motor cylinder contains ausualy reciprocatory 1 hammer vpiston -for percussivelyk actuating a drill steel 6 suitably mounted in a front chuck-housing lsuitably attached to the .front end ofthe motorAV cylinder. The* drill. steel Y'carries a usual detachable drill bit 8 having a rearwardly facing shoulder 9 of larger diameter than the .steel body.

rIhe `hammer motor may be fed along the shell I guidewaysin any conventional Vmanner,4 either manually or Aby power, and in this instance, a conventional1motor drivenfeed screwl, journaled onA theguide shellr is employed to feed the hammer motor. Since, as above stated, the rockdrill is of a conventional design and is Well known to. those skilledin the art, further dis-` closure thereof is herein unnecessary.

Nowv referring to the embodiment of the inven-f, tion shown in Figs. 1 to,7 inclusive, it will be observed that attached as by bolts I2, herein three in numbentothe forward end of the guideshell 3A are parallel front and rear transverse end-plates i3 and I4 held in proper spaced relation by spacing sleeves I5 and I6 surrounding the bolts between the. plates. Formed integral with the rear end-,plate I4 is aA centrallyrlocated bearing boss c Il in which a front bearing portion I8 of the feed v screw I9 is journaled as shown in Fig. 6,. Pivotally and slidably ,mounted on the spacing sleeves l5, I 5 of the upper pair of bolts intermediatethe plates, is a pair ofcooperatingguide arms I9, I9

@ach having flimpiarciprifitely Shapedguidns portion ,Zilvfor engaging the drilld steel. These guide` arms are provided with bearing hubs 2I. pivotally mountedl on the upper spacing sleeves and swingable abouttheir pivotal mountings intoand Vout of steel guiding position.V The steel guiding portions 2u of the guide arms,A whenv the latter areV in their closed position asyshown in Figf 3,`m brace the body ofthe drill steel to hold Ythe latter centered during starting `r= spotting of a drill hole inthe manner 'well known to those skilled in the art. The wideopen, non-guiding position of the arms is shownin Figfl and, in this position, the' arms are swung" laterally outside the shell guideways so that the chuck 'housing' may move forwardly between the arms.

lIn this illustrative construction, the bearing hubs- 2Iof the 'guideV arms are mounted on 'the integralwith the lower spacing sleeve I6. This lower spacing sleeve I6 is formed at its ends with toothlike projections 39 which are rigidly interlocked with 'the' end plates so that the locking and stop member- 29 is held against rotation. When the guide arms are moved bodily longitudinally'along the upper spacing sleeves either forwardly or rearwardly,the-lockinglugs 2l are releasedfrom thevertical sides of the member 29, and,'at that time, the torsion spring acts automatically to swing the arms wide apart. The locking and stop member'29is cut away at 3l near its ends to provide clearance lfor the locking lugs to permit the latter to swing freely past the lockingl member as the arms swing apart. The arm-hubs have spaced projections 32 for engaging Ithe sides of the locking and stop member 29 to limitoutward swinging movement of the arms. As shown, the guiding portions 29 of the arms have front and rear projecting bosses 33 and 34 with which the drill bit and chuck housingare 46 `iadapted'directly-to engage to move the guide arms bodily either forwardly or rearwardlyout of their centrally, located, locked position. guide armslare in .either their forward or rear-. ward'position and are unlocked from the lockinglmember'29, the torsion spring 23 quickly swings 'steel aszshown in Figs. 2 and 3, and theV arms maythenbe-v shoved bodilyv longitudinally along the upper spacing sleeves I5, I5 into the centrally located/position shown in Fig. 1, with the locking projections 21 on the' arms abutting the vertical sides 23 of the locking and stop member 29. -The coilsprings-22 and 23 serve to hold the arms in this centrally located position andthe torsion spring 23 holds the lugs tightly against the sides p of thelocking member. As the hammer motoris i fed -forwardly along the guideways of the guide shell to feed the drill bit 8 toward the work, the forwardy endof the chuck housing 'I engages the ?therebyto release the locking lugs 21 from the vertical sides 28 of the locking member 29. The

torsion spring then acts quickly to swing the' guidelarms .l apart .into their wide-open, non'- guidingposition shown in Fig. 4, so that, upon continued forwardV movement of the hammer- When the madame motor, the chuck housing may: move between. the guide arms forwardly" past the guide. When the drill hole is started or spotted with ai short. drill steel and for instance, in a, Wagoner mwenl drill, it. is also desirable to. have the guide opere automatically as the drill. bit isz retraeted fmm the work, and during rearward movemennet hammer motor along thet shell. guideways; the rearwardly facing shoulder 9l on the drilli bili l engages the. frontbosses 33 on the mde-.arma tu move the latte-r bodily rearwardly' along.; time upperspacing sleeves |;5,. |15 to; release the@ leem lugs 2.1. from locking engagement;vizitlrnthek lacking; member 12.9.. Whenthe. guide. arms; arev the torsion spring 23 acts quicklyi torI swing the arms. wide apart so that upon continued rearward movement. of the hammer motion the bit may. move rearwardly past; thegnidebetweemthe; guide arms. It is accordingly eydenh that. iure-.-v spective of the direction or incitement; ot the hammerl motor along the shell?. guidewaysi. the;Y guide arms are. automatically.'l releasedi from the drill steel thereby to preyentiaccidental-contaci, oi the, chuck. housing or the drill'hit. with` guide arms while-the. latter are, held closed. which. might. result. in damage; to the. drilli.

In the. embodiment. of, the inve-entiere sl'iownrinY Figs. 8 to 13 inclusive a pair of front and. rear: transverse. end-plates 36 and 3l are attached, as by. bolts, 38;, herein threein numben, tei thermi-v ward end of, the guide shell 31andfithe1platesaree maintained in proper spaced. relation. by spacing; sleeves 38 surrounding the: beltsV between plates. Pivotally. mounted on the pain of; upper. sleeves 3,9 is a pair of coopetat-inge guide arm-s; d; 40 having appropriately: shaped portions M; for. engaging: the,l drill. steel.. In. instance., the. guide arms have. no; bodily. sliding: moxnement. and. areconned solely, to. swinging; mdvemenlz in. transverse` planes.. The guidearms haveebeane. ing nulosM 4 2f which areheldagainstthee reanplata 31 by a spring 43 hav-ing` coils. surrnunriingt; the upper spacing sleeves between. the` nearing; hubs and thefront plate. 316.. The spring coils; aref' connected by a cross. portiom M and have their` ends, engaging. at; 45 the; guide. 'Ehissprinni is of the combined compression; and; torsion-time: and serves: not; only to; swing: the: guide:7 armsv apart, but: also yeldngly tdholcl,the',guidel anms; rearwardly against. thearean end-platee. This-item.- sionf springy constantly,i urges. the. guider. arms; toward. their. wide-open, non-guiding position; shownin Fig. 1l, and. projeetionsk on thel'arm. hubs engage the` lower.- sides; of: the. bearings. boss. llf to limitv outward: swinging movement ot'. the:

arms.

The guiding portions. 4;Ii. of; oney ot' the. guide. arms is# formed; withelaterali proieeticmsv Wipro.- viding a longitudinalf guideways-v whicln neeeivea a. longitudinal shiftable; latohz. or-r lock; Whenl the guide arms: aresxinmgv togethen int. their steel guiding; position. shown; Eig; 111;] ai lug 5i) on. the latch bal'.v may; be movedintoz.en'.- gagement, with. ai prniection4r Sil l onztheobhervguide arm. rigidly to'lockrthearms' together.: 'Ihe-elatch bar. has; downwardly bent'. end. portions 52e' whichextenchinto adjacency toithefsteelbodyfim the-manner. shown. soithatnthelatchy barmatebes shifted. longitudinally either-A forwardly.;v on rear* wardly. by..v direct: engagement-l. off the chuclif house-V ing. or the .drill bitrv therewith; springg-presse@` plunger. 53. onv the guide'.l arm-I wlriichi carriesY the latch bar, engages a suitablel dei-,enti 513 oneth'ee ban yieldinglyl toi` hold". the; latter eentrallyrinits lacking? position mode. of operation. ofY this; modified. enr-I bodiment. is.t as: follows; As the hammerv motor. is fed-forWardly along. the shell; guid'eways: dur:- ingr leed, of: the: dri-lll. bit towardy work; the

. front. endci? the chuck housing 1i engages the vmision; springv acts* quickly to swing the arms.

about their pivotsr into: the. wide-open, non-guidingposition. shown in 11 so that', as forward:`

feed of: the hammer motor continues, the chuck'. henslng may move forwardly between. the guide beyondv the guide. As. the. hammer.' motor isfed rearwardly along thee shell. guideways dur ing; retraction of the drill` bit. from the; world,

'subsequently to@ thev spotting of ahnle with. a.

,i to; swing: the. armsy wide apartso thatr uponv continued rearward movement-.of the, hammer motor.' the drill'. bili may.: move rearwardly between the'v guide arms pase the guide.

As; a, result ot this. invention, it will' be. noted; that'v an. improved drill` steel guide is. provided. Whitlr is automaticallyreleased.v from guiding relation:= with, the drill. steel. when. the hammerxmo'- tonassnmes.-arpredetermined; position on its guiding support, during either..l forward or reverse:

moiement. thereof; along the support guideways."`

ItA wi1i furt'lrer'i be evident that.bymounting. the.

guide; arms so: that theyf may move bodily either.

forwardly on rearwardly from ai centrally locateda. lockedspositioni, the guide arms may be automati cally;` released: from.- the drill steel byl directA errgagementz of*` the. chuck housing or thedrill: bit.l with. the g l1icle.;amns; It. willfurther. be evident. that; the provision of@ the improved. manner of mounting andzarrangementtof. the guide' arms; theflatter"areautomatically moved into' their releasedi nom-guiding: position: during' feed off the: drillingf.motor in'.v either.y ci: opposite directions; in, an extremely.: effective. manner. Fur-ther'y byevfeeting'; release; of the guide arms by.' direct` engagement; of; the.)r hammer: motor.l orv drilll bit therewitm, all complicated release. and.V actuating. devices@ are eliminated. Other uses z and'advan' taesa ofi' the. improved drill.: steel; guide'. will; be.` clearlyappa-rent..r to., those skilled4 in. the-art..

lll-lille.:A therey are: in;` this application. specifically;u described. two forms. which'v the; invention] may,n assume'- inpractice;l it; will be understoodI that..

theseA forms; of the same are shownior.` purposes;

yieldingly holding said.. guiding element. in.v af.y centrallylocated position longitudinally of saidf.

Sulmona;x meansv for locking` saidguiding element:- in; steel: guiding; positionI when. in4 said4 centralllocated position; said'A locking means beingreleasable upon bodily movement-of said guiding element either forwardly or rearwardly fromf said centrally located position relative.to said support, and means for automatically moving said guiding element out of .steeli guidingpositionV when said locking meansisreleased; 3 w

2. In ak rock drill,` a support providinga longitudinal. guideway, a. drill-lsteel'actuator -movable longitudinally along said support. guideway and adapted to actuate a drill `steel carrying av drill4 bit, and a drill steel guide mounted on said sup.-

portand including aguiding -elementfmovabla into` and out of steel guidingposition', means for' locking said guiding element in ysteelcguiding position, .said locking means being.- releasable either by direct engagement of saidactuator with said guiding element or of said drill bit with saidV guiding element, andv means operableindependently of movement of said actuator or saidfbit with respect to said supportforz automatically moving said guiding elementV into non-guidingy position out of the path ofmovement of said actuator or said bit whensaid locking .means is.

released. .3.. In a rock drill,asupport providing a longitudinal guideway, a vdrill steel actuator movable longitudinally along said support guideway-and adapted to actuate a drill steel carrying a drillbit, and a drill steel guide mounted on said support and including a guiding .element movable into and out of steel guidingposition, means for lockingsaid guiding .element in steel. guiding.

position and including a reciprocable lock release element movable longitudinally of said support,` and having a portion engageable directly by said actuator .as the` latter moves forwardly along said support guideway .and another portion engageable directly by said vdrill bit as said actua-tor moves rearwardly along said support vguideway,` said lock release element effecting release of s'aid locking means upon either direction of movement thereof, and means for. automatically moving' said guiding element into non-guiding position..-

whensaid locking means is released.

4. In a rock drill, a support providinga longitudinal guideway, la drill steel actuator movable'l forwardly and rearwardlyalong said :supportg-uideway and adapted to actuate a drill bit,` and: a drill steel guide mountedonsaid support and;

including a guiding elementmovable into and out of steelguiding position, said guiding element being movable bodily forwardly and-rear-f." Y wardly from a centrally located position longitudinally relativetosaid support, meansior locking said guiding element whenin itsfcentrally located position in guidingrelation with the drill steel, said locking means being releasable 'either by direct engagement of saidsteel actuator with said'guiding elementas said actuator moves forwardly along said guideway or bydirect engagement of the drill bit with said guidingeleinent` during rearward movement of said' actuatoralong saidguideway, and means for moving'said guiding element out of guiding relation with the drill steel when said locking means is released.

' 5. In a rock drill, a support providing a longi-4 tudinal guidewaya drill steel actuator movable' forwardly and rearwardly along 'said "support guideway and adapted to actuate a drill steel,

carrying Va drill bit, and a drill'steel 'guide mounted on said support and including 'a,guid ing element movable into and out ofsteel guiding position, said guiding element being movable; bodily forwardly andy rearwardlyfroin a'cent'rallyf located position longitudinallyrelative to saidV support, mean'sifor Yyieldingly holding said guiding f elementninpits centrally located position, means -for-lockingsaid.guiding element when in its centrally llocatedposition in guiding relation with theY drillsteel,vsaid locking means being releasable'eithenby direct engagement of said steel actuatorwith said guiding element as said actuator moves forwardly along said guideway or by direct engagement of the `drill bit with said guiding-element. during rearward movement of said-'actuator along-said guideway, and means formoving` said. guiding element outof guiding relation-,with the: drillsteel when said locking meansiis releasedx, i

:.'6.1-."In -a drillsteel guide, a support, a guiding elementrmounted on said support and movablev located' position bodily longitudinally relative to said support, andmeans for locking said guiding elementtin steel guiding position when the same is inits centrally located position on said support,. said locking means being releasable upon bodily movement of said guiding element in either rdirectionlongitudinally relative to said supporti. I

7. Ina drill steel guide, a support, a guiding element mounted-.on said support and movable relativethereto into and out of steel guiding position, said guiding element also being movable eitherfforwardly orv rearwardly from a centrally. located positionbodily longitudinally relative to said-supportand yieldingly holding said guiding .element-in said. centrally. located position-,and means for locking saidguiding element invsteelguiding. position-when the same is in its centrally locatedposition on said support, said locking means being releasable upon bodily movementof. said guiding element in either direction longitudinally 'of said support.r

In, a'zdrill .steel guide, a support, a guiding elementmounted on said support and movable relative thereto into and out of steel guiding position said guiding element also being movable eitherforwardly orrearwardly from a centrally locatediposition bodily longitudinally relative to said support, and means for locking said guiding element in steel guiding position when the same is `in-its centrally located position on said support, saidlocking means being releasable upon bodily movement of said guiding element in either direction longitudinally of said support,A and meansfor automatically moving said guiding element out of its steel guiding position when said locking means is released.

9..'.In a drill steel guide, asupport, a steel guiding element mounted' on said support and movable relative thereto .into and out of steel guiding position, and .means for lockingsaid guiding element in its steel guiding position movable longitudinally either forwardly or rearwardly relative Ato said support into released position.

l0. In a drill steel guide, a support. a guiding element mounted onv said support and movable relative thereto into and out of steel guiding position, andmeans for locking said guiding element in itssteel guiding, position including a shiftable lock releasing element mountedv on said guiding means .and movablelongitudinally either forwardly or rearwardly relative to said support into lock releasing position..

lL-ln a drill steel., guide, a support, a steel guidingmeans mounted on said support and.

movable into and out of steel guiding position, said guiding means being movable bodily longitudinally relative to said support either forwardly or rearwardly from a centrally located position,

and means for vlocking said Aguiding means in steel guiding means mounted on said support and movable into and out of steel guiding position, said guidingmeans being movable bodily longitudinally relative to said support either forwardly;

or rearwardly from a centrally located position, means for yieldingly holding said guiding means in its centrally located position, and means for locking said guiding means in steel guiding position when the same is in said centrally located position, said locking means being releasable upon bodily movement of said guiding means in either direction from said centrally located position.

13. In a rock drill, a support providing a longitudinal guideway, a drill steel actuator movable longitudinally either forwardly or rearwardly along said support guideway and adapted to actuate a drill steel carrying a drill bit, and a drill steel guide mounted on said support and including steel guiding means movable into and out of steel guiding position, and means for locking said guiding means in steel guiding position, said locking means being releasable either by direct engagement of said guiding means by said steel actuator as the latter moves forwardly along said support guideway or by direct engagement of said guiding means by the drill bit as said actuator moves rearwardly along said support guideway, said guiding means being movable upon release of said locking means out of the path of movement of said actuator or said bit.

14. In a rock drill, a support providing a longitudinal guideway, a drill steel actuator movable longitudinally either forwardly or rearwardly along said support guideway and adapted to actuate a drill steel carrying a drill bit, and a drill steel guide mounted on said support including steel guiding means movable into and out of steel guiding position, said guiding means also being movable bodily either forwardly or rearwardly from a centrally located position longitudinally relative to said support, and means for locking said guiding means in steel guiding position when the same is centrally located and releasable upon bodily movement of said guiding means in either direction, said locking means being releasable rect engagement with said releasing element by said steel actuator as the latter moves forwardly along said support guideway or by direct engagement with said releasing element by the drill bit as said steel actuator moves rearwardly v'along said support guideway.

16. In a drill steel guide, :a support, steel guiding `means mounted on said support 'and movable bodily either forwardly or rearwardly 'from a `centrally located steel guiding position :longitudinally relative 'to said support, fand means for locking said :guiding means in guiding relation with the drill steel when .in'said centrally located .steel :guiding position, said locking means being .releasable upon bodily movement of said guiding means in either direction.

17. In a rock drill, a support providing a longitudinal guideway, a drill steel actuator for actuating the drill steel carrying a, drill bit and movable back and forth along said support guideway, a drill steel guide mounted on said support, and means for locking saidk guide in its steel guiding position releasable automatically either by direct engagement of the steel actuator with said guide as said steel actuator moves forwardly along side guideway or by direct engagement with said guide by the drill bit as said steel actuator moves rearwardly along said guideway.

18. In a drill steel guide, a support, a drill steel guiding means mounted on said support and movable bodily either forwardly or rearwardly longitudinally relative thereto from a centrally located position, and means operative when said guiding means is in said centrally located position for holding said guiding means in guiding relation with a drill steel, said holding means being releasable automatically to free said guiding means from steel engagement upon movement of said guiding means either forwardly or rearwardly from said centrally located position.

19. In a drill steel guide, a pair of cooperating steel guiding elements mounted for bodily movement in opposite directions, and means for locking said guiding elements in guiding relation with a drill steel including a stationary locking member, and locking projections on said guiding elements engaging said locking member, said locking projections being releasable from said locking member to free said guiding elements from guiding relation with the drill steel upon bodily movement of said guiding elements in either direction.

either by direct engagement of said guiding' means by said steel actuator as the latter moves forwardly along said support guideway or by direct engagement of said guiding means by the drill bit as said actuator moves rearwardly along said support guideway.

l5. In a rock drill, a support providing a longitudinal guideway, a drill steel actuator movable longitudinally either forwardly or rearwardly along said support guideway and adapted to actuate a drill steel carrying a drill bit, and a drill steel guide mounted on said support including steel guiding means movable into and out of steel guiding position, and means for locking said guiding means in steel guiding position including a lock releasing element movable bodily either forwardly or rearwardly from a centrally located position longitudinally relative to said supprt, said locking means being releasable either by d- 20. In a drill steel guide, a pair of cooperating steel guiding elements, and means for locking said elements in guiding relation with a drill steel including a reciprocable latch mounted on one guiding element and engageable with a locking projection on said other guiding element, and

releasable to free said guiding elements for movement out of steel guiding relation upon movement of said latch in either of opposite directions from a centrally located locking position.

21. In a rock drill, a support providing a longitudinal guideway, la drill steel actuator movable longitudinally along said support guideway and adapted to actuate 'a drill steel carrying a drill bit, a drill steel guide mounted on said support and including a guiding element movable into and out of steel guiding position about an axis parallel to the drill steel axis, means for locking said guiding element in steel guiding position including a locking member coacting with said element, said guiding element being locked in steel guiding position when said locking member and said guiding element are in a predetermined relative Aposition and being releasable by relative movement between.y the same and said locking member in either-of opposite directions from such position, and means for automatically moving said guiding element into non-guiding.

position When said locking means is released.

22.In a rock drill, a support providing a longitudinal guideway, a drill steel actuator movable longitudinally 'along said support guideway and adapted to actuate a drill steel carrying aV drill bit, a drill steel guide mountedV on said support and including a guiding member movable into and out of steel guiding position, means for locking said guiding member in steel guiding with said guiding member, said guiding member -lbein'g positively locked against movement away from .the steel when said locking member and said guiding member are in a predetermined relative'position from which one of them is movable I in either of opposite directions to effect release of position including a locking member coacting, 15 

